Fork Top Nuts

[andy120t]

My CB650 runs 35mm forks that slot into a set of Cb550 yokes. They have various air assist elements on them (pipes, valves etc) that look messy, foul my handlebars & that I don't really want.

Anyway, I thought that rather than try to blank off the various holes it might be simpler and easier to replace the nuts at the top of the stanchions with some "standard" ones.

My questions is,  does anyone know if these fittings / threads for these nuts are the same size for my bike as for the 550? If so, can I just pick up a set of nuts from the more common 550 stanchions and use those?

...and here's a piccie of the RHS fork top so you can see the nut/fittings I want to eliminate. The air valve sticks up and fouls the handlebars when it's in the right position and there should also be a pipe (similar to an old style bicycle pump end fitting) that runs from the hole under the valve to the other fork top.



Thanks in advance!
Andy

[Bryanj]

Can't be certain as Honda bought in a lot of forks but if they are the same diameter chances are the threads are the same, if bigger probably not

[Yoshi823]

Those air fork caps are very similar to the CBX550F2 ones that I had fitted to the CBX1000ZA forks on my 750/823F2. The Schraeder valve is as per the air valve on the tyres, so not old at all. If you want clean, the fork tops from a CBX1000ZA would fit perfectly, with a small black cap that screws into the fork top. I might have some in my box of bits in the shed. I'll have a look when I can fight my way past the snow to get to the shed...

[andy120t]

Be great to know what thread & diameter they are. ..... possibly a piccie if you can battle through the snow?! Thanks.

[lordwhimsey]

CB550 fork top nuts are a 28mm x 1.5mm thread



Should poke up about 12mm above the top of your forks and stick 24mm into them, 36 mm overall length.

Hope this helps.

[andy120t]

Thank-you! I'll check the dimensions over the weekend.

[andy120t]

Photo of the CB650 version. These are the same thread - 1.5mm but the diameter is different at 31mm, as shown in the piccie.

Seems odd that they are the same diameter forks but quite different diameter nuts?



I may just revert to Plan A which is to find the right sized bolts & copper washers to replace the air valves. For this I need anthree  M8 x 1.0 (see piccie - is that metric fine?) which will replace the brass valve in the piccie, & also use them to fill the two holes where the air balance pipes enter the fork tops, so if anyone has any spares of this size...please let me know.     

All my M8 bolts seem to be x1.25 and local hardware shops aren't what they used to be.

[SteveD CB500K0]

Thinner tubes = less weight?

[K2-K6]

You may have a problem finding any off the shelf fine pitch metric stuff.

As  stop gap you could cut the protruding part above the the brass hex off the existing and make some brass plugs up to fit the bore then solder them in to in effect "make" a bolt.

[BigAl (Alan)]

The CB750 K0-K6 are 28mm, I replaced 2 last year on my K4. Hope the information helps

Alan

[Yoshi823]

These are the ones from my CBX1000ZA fork legs that I used CBX550F2 air fork caps in. They have the same size threads as the ones shown in the photos & come with the black plated cap plates. I don't think that I have the 'O' rings but if you want them for

[andy120t]

....I've been meaning to mention that my wife bought me the mother of all tap-and-die kits for my birthday. Quality not quantity, I always say but the ladies seem to thing bigger is better...so this kit has everything. I'll post a piccie soon, the point being, I've now started cutting my own bolts (m8x1.0), using some long M8 bolts where the top of the shank is smooth.

First one worked a treat - beginners luck - and now it and a copper washer are in place in the fork top. The second one the thread was cut at a crazy angle...but I'll keep at it as it's a good skill to have. Pics to follow.

Yoshi - your fork tops diameter? See my picture for the dimensions on my current ones - your gauge shows c.28mm (?) ..I need 30.78  (is that 30 or 31?). Anyway, can you let me know what yours are. I'll probably go with my home-cut bolts for now but be nice to have some tidier fork-tops in reserve too - thanks!

[K2-K6]

Sounds like a good present Andy, have you got any pro-lubrication for it? I've always used some called "rocol" I think, and it makes for really smooth cuts.

[Yoshi823]

My vernier measurement is the same as yours...the figure is where it's adjacent to the '0' mark, which is just below the 31mm...don't know how you read 28mm though.

PM sent just before I read this post.

[andy120t]

Cheers Yoshi - I've swapped in the ones you sent & they fit perfectly;  and now so do my handlebars.